1. Field of the Invention
The present invention relates to an ink jet recording apparatus that performs a recording operation by discharging recording liquid, such as ink, from the discharge ports for the formation of liquid droplets.
The present invention is applicable to such an apparatus as a printer for recording on paper, thread, fiber, cloth, leather, plastics, glass, woods, ceramics, and other recording mediums, a copying machine, a facsimile equipment provided with communication systems, and a word processor having printing unit. Further, the invention is applicable to an industrial recording system combined complexly with various kinds of processing apparatuses. Here, the term xe2x80x9crecordingxe2x80x9d referred to in the specification hereof not only means the provision of meaningful images for a recording medium, such as characters and graphics, but also, it means the provision of such meaningless images as patterns, among some others.
2. Related Background Art
The ink jet recording apparatus is a recording apparatus of the so-called non-impact recording type capable of recording on various kinds of recording mediums at high speed, which is characterized in that the apparatus generates almost no noises during the recording operation. With such advantages, the ink jet recording apparatus is widely adopted as the one that bears recording mechanism for a printer, a copying machine, a facsimile equipment, a word process, or the like.
As the typical ink discharge method for the recording head mounted on an ink jet recording apparatus of the kind, there has been known the one which uses electromechanical converting devices, such as piezoelectric elements, the one that uses the irradiation of laser or some other electromagnetic waves to generate heat for discharging ink droplets by the action of heat thus generated, or the one that uses the electrothermal converting devices having heat generating resistive elements to give heat to ink for discharging ink droplets by the action of film boiling. The ink jet recording head that uses the electrothermal converting devices provides each electrothermal converting device for the interior of each recording liquid chamber, and then, supplies electric pulses serving as recording signals to each of them, respectively, in order to generate heat for the provision of thermal energy for ink. Thus, with the utilization of bubbling pressure exerted when recording liquid is bubbled (at the time of film boiling), which creates the phasic changes of the recording liquid then. In this way, recording is made on a recording medium. The apparatus is generally provided with ink jet recording nozzles for discharging ink droplets, and the supply system that supplies ink to the nozzles.
The recording apparatus which is provided with an ink jet recording head of the kind is capable of outputting characters and images in high quality at low costs.
With such advantages as to output color prints at lower costs, this recording apparatus of the so-called BJ type has conventionally been in wide use. The recording apparatus is based on the discharge principle of bubble jet type proposed by Canon Kabushiki Kaisha, the applicant hereof, where liquid droplets are discharged along the formation of each bubble (generation, growth, defoaming (debubling), and extinction). This recording apparatus uses the bubble jet method adopted commonly for each of the recording element substrates that discharges black ink as black liquid, and cyan, magenta, and yellow ink as liquid of respective colors.
Here, it is required more, in general, to provide images in a higher quality, and to need such requirement, the number of discharge ports for each recording element substrate tends to increase from 64 ports to 128 ports, 256 ports, and so on, and arranged in a higher density in terms of the xe2x80x9cdpi.xe2x80x9d which stands for the number of discharge ports per inch, such as 300 dpi, 600 dpi, and so on. The heat generating element, which serves as the electrothermal converting device to be arranged for the discharge ports, responds to the pulse driving of several psec order to 10 xcexcsec order, and forms bubbles by means of film boiling. Then, this element can be driven at high frequency to enable the high speed printing and the formation of high quality images to be attained. In recent years, therefore, the number of heat generating elements, which should be driven per unit time, tends to be increased.
For the conventional ink jet recording head, a plurality of ink discharge ports are incorporated on the same flat plane of one silicon substrate by use of the semiconductor manufacturing technology and technique. As a result, the front face (discharge port surface) of the discharge formation member is formed almost flat uniformly on the silicon substrate. With the formation of such discharge port formation member on the flat surface of the silicon substrate, a chip, which serves as the recording element substrate, is completed. The chip is adhesively bonded or bonded to the structural member under pressure for fixation. At the same time, a member provided with ink flow paths is bonded in order to supply ink. Further, the wiring member that supplies electric signals is arranged in a specific direction around the recording element substrate.
When a color recording is made by this ink jet recording head, color ink (usually, three kinds of cyan, magenta, and yellow) and black ink are discharged, but it is sometimes preferable to make the discharge amounts and other conditions different for color ink and black ink. In other words, in order to attain recording in colors in a high quality at the same level as that of a silver salt photography, it is necessary to make dots small enough so as not to be seen on a recording sheet (in a granular sense). Thus, it is preferable to make the liquid droplet of color ink extremely fine. As to black ink, too, it is preferable to form small dots on the recording sheet by the provision of fine liquid droplets in consideration of the enhancement of resolution and sharpness of characters. However, there are often the cases where a designated area should be solidly painted in addition to characters and the like to be recorded, that is, the so-called solid printing is made often. If the solid printing should be made by discharges of finer liquid droplets, the discharge frequency becomes higher inevitably, requiring a longer recording time. It is therefore preferable to make arrangement so that black ink can be discharged in larger liquid droplets than those of the other color ink.
When the discharge amounts of black ink and other color ink are made different like this, it is conceivable that the recording heads should be structured separately each individually for use of black ink and that of other color ink. However, when a recording apparatus is completed by installing a plurality of individual recording heads on the recording apparatus, the distance between the element substrates becomes greater in the main scanning direction inevitably, leading to a problem that the width of the carriage main scan becomes larger to the extent that the entire width of the separated recording element substrates becomes greater. In this respect, if the recording element substrate for use of color ink and the recording element substrate for use of black ink are arranged closely to make them a single recording head instead of structuring plural recording heads to be separated each individually, it presents new and effective means. In this case, the recording element substrate for use of color ink and the recording element substrate for use of black ink should be produced by use of different recording element substrates. Particularly, when the discharge amounts must be made different for color ink and black ink, it is inevitable to produce the substrates separately, because the diameter of each discharge port is often made different per recording element substrate, and the distance between the discharge heater (electrothermal converting device) and the discharge port becomes different, too, and the resultant thickness of recording element substrates becomes different inevitable.
For the usual ink jet recording apparatus, a cap member is provided to cover the front side of discharge ports in order to prevent ink from being evaporated and solidified around the discharge ports when the apparatus is not in use or to receive ink when predischarges are performed for removing mixed particles and the like together with ink bubbles, before recording. For the conventional recording apparatus, the main current of structure in this respect is that either capping is arranged on the discharge port surface or on the wiring member that surrounds a single recording substrate. For the ink jet recording apparatus which is structured to use piezoelectric elements, too, it is the main current to structure capping on the entire surface of a uniformly flat orifice plate. This is because the cap member must be in close contact with the uniformly flat surface or the smoothly continuous flat surface in order to obtain the anticipated capping effect by covering the circumference of discharge ports by use of the cap member.
As shown in FIG. 27 and FIG. 28, the main current of the structure of the conventional ink jet recording head is the one in which plural recording element substrates 200 and 201 are adhesively bonded to each of the correspondingly separated structural members 202 and 203, respectively. The structure of the recording head provided with plural recording element substrates 200 and 201, which are capable of obtaining different discharge amounts, makes it inevitable to position the flat surfaces where each of the recording element substrates 200 and 201 is installed, respectively, to be considerably apart from each other. As a result, capping cannot be implemented by use of one and the same cap. The structure should become such that capping is effectuated by use of each of the individual cap members 204 and 205. There is no consideration at all, either, as to the difference in the thickness of recording element substrates 200 and 201, which is brought about by the difference in the discharge amount. This is also another one of reasons here.
One of the objects of the present invention is to provide an ink jet recording apparatus to be made smaller at lower costs by using an integrated cap member to cap recording heads on a substantially even flat plane simultaneously, while being provided with a plurality of recording element substrates having different amounts of ink discharges, respectively.
The other object of the present invention is to provide an ink jet recording apparatus which comprises an ink jet recording head provided with a plurality of recording elements for generating energy to be utilized for discharging ink, a plurality of flow paths for retaining ink to receive the energy, a plurality of ink discharge ports for discharging ink, and a plurality of recording element substrates, and a cap member for capping the discharge ports of the ink jet recording head, and in which the plurality of recording element substrates having the thickness of one recording element substrate thereof being different from that of the other recording element substrate are arranged adjacent to each other on a substantially even flat plane, and the cap member is capable of capping the discharge ports of the plurality of recording element bases plates altogether on the essentially uniform flat plane.
With the structure thus arranged, it becomes possible to simply cap the ink jet recording heads having a plurality of recording element bases plates which are different in thickness and discharge characteristics. As a result, the recording apparatus can be made significantly smaller at lower costs. In other words, for the serial printer where an ink jet recording head scans, the interval between recording element substrates can be made as close as possible in the main scanning direction, hence making the scanning width smaller in the main scanning direction. Further, when the capping mechanism and others are arranged in the non-recording area in the main scanning direction, the smaller the interval between a plurality of recording element substrates, the smaller becomes the width of the capping mechanism and others. This presents an extremely significant advantage for the ultra-small portable printer or the like.
The cap member may be the one that performs capping with the ribs thereof being closely in contact with the flat plane. In this case, the ribs of the cap member forms a single capping space being surrounded thereby so that capping may be performed by positioning the discharge ports of the plurality of recording element substrates in the single capping space or a plurality of capping spaces are formed by being surrounded by the ribs of the cap member, and the discharge ports of the recording element substrates are positioned respectively in the plurality of capping spaces to perform capping. Further, in this case, at least a part of the ribs positioned at the boundary of the plurality of capping spaces may be made to be a contour line commonly possessed by the plurality of capping spaces.
It is preferable to make the distance between the recording element and the discharge port on the recording substrate having black liquid being supplied thereto as ink is relatively long, and the distance between the recording element and the discharge port on the recording substrate having color liquid being supplied thereto as ink relatively short. Then, it is preferable to make the discharge amount of liquid discharged from the discharge port on the recording element substrate having black liquid being supplied thereto as ink relatively large, and the discharge amount of liquid discharged from the discharge port on the recording element substrate having color liquid being supplied thereto as ink relatively small.
With the structure thus arranged, it becomes possible to perform a solid printing at a high speed by discharging large liquid droplets of black recording liquid, while it is possible to perform a high quality recording in high precision by discharging small liquid droplets of color recording liquid.
Also, it may be possible to arrange the structure so that the liquid discharge method of the recording element on the recording element substrate having black liquid being supplied thereto as ink generates bubbling in ink by action of the recording element, and extinguishes bubbling by defoaming the bubble formed by such bubbling, and the liquid discharge method of the recording element on the recording element substrate having color liquid being supplied thereto as ink enables the bubble formed by bubbling to be communicated with the outside through the discharge port when ink is bubbled by action of the recording element. With the structure thus arranged, the bubbling pressure escapes outside after color recording liquid is discharged to make the vibrations of meniscus smaller at the time of debubbling. Then, refilling can be performed quickly, which contributes to the execution of a higher speed recording.
A plurality of recording element substrates are provided with the substrates of substantially the same thickness arranged on one and the same plane, and discharge port formation members laminated on the substrates, and then, the distance between the recording element and the discharge port of at least one of the recording element substrate may be made different owing to the different height of the discharge port formation member thereof form that of the other recording element substrate.
In accordance with the present invention, it is possible to provide one ink jet recording head with a plurality of recording element substrates each having different distance between the recording element and discharge port, respectively. As a result, each individual recording element substrate having different discharge method or different amount of discharges, respectively, can be arranged one integrally formed ultra-small recording head without preparing a plurality of ink jet recording heads. Therefore, black ink forms large liquid droplets, while color ink forms small liquid droplets. Thus, recording in black ink is performed efficiently at a higher speed, while recording in color ink can be made in a higher quality. Then, a plurality of recording element substrates can be capped easily with one integrally formed cap member reliably. Further, with a simple structure, the recording element substrates themselves can be arranged as closely as possible to make the recording head itself smaller as a matter of course, and also, make the main scanning width of the recording head itself narrower significantly. Consequently, there is no fear at all that the apparatus becomes larger, while making it possible to suppress the costs of manufacture.